Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Quando pskov é oblast\age, qual é o resultado de 18 a 19?
 ###Tabelas: CREATE TABLE births_and_deaths (births_and_deaths_id AUTO_INCREMENT PRIMARY KEY, Average population (x 1000) VARCHAR, Live births 1 VARCHAR, Deaths 1 VARCHAR, Natural change 1 VARCHAR, Crude birth rate (per 1000) INT, Crude death rate (per 1000) INT, Natural change (per 1000) INT) CREATE TABLE paracanoe (paracanoe_id AUTO_INCREMENT PRIMARY KEY, Rank VARCHAR, Nation VARCHAR, Gold INT, Silver INT, Bronze INT, Total INT) CREATE TABLE 2.ukrainians (2.ukrainians_id AUTO_INCREMENT PRIMARY KEY, C/W 15+ INT, Oblast\Age VARCHAR, 15 to 17 INT, 18 to 19 VARCHAR, 20 to 24 INT, 25 to 29 INT, 30 to 34 INT, 35 to 39 INT, 40 to 44 INT, 45 to 49 INT, 50 to 54 INT, 55 to 59 INT, 60 to 64 INT, 65 to 69 INT, 70+ INT) CREATE TABLE all-time_series_records_against_big_12_members (all-time_series_records_against_big_12_members_id AUTO_INCREMENT PRIMARY KEY, Texas vs. VARCHAR, Overall Record VARCHAR, at Austin VARCHAR, at Opponent's Venue VARCHAR, at Neutral Site VARCHAR, Last 5 Meetings VARCHAR, Last 10 Meetings VARCHAR, Current Streak VARCHAR) CREATE TABLE winfield_triple_challenge (winfield_triple_challenge_id AUTO_INCREMENT PRIMARY KEY, Driver VARCHAR, Race 1 INT, Race 2 VARCHAR, Race 3 VARCHAR, Points INT)  
SELECT 18 to 19 FROM 2.ukrainians WHERE Oblast\Age = Pskov